SYSTEMATIC REVISION 45 



rupted by the foramen at about the middle. The next largest bone is the 

 tabular, which extends half the length of the parietal forwards. The supra- 

 mastoid is pyriform, is rather small, and its anterior angle is wedged in 

 between the posterior parts of the postfrontal and postorbital. The post- 

 frontals separate the frontals from the orbital border. The frontals are 

 distinct and their posterior border is about in the line of the posterior borders 

 of the orbits. The supratemporal region is injured, and only the suture 

 between the quadratojugal and the jugal is visible. 



"The sculpture consists of radiating ridges from some point in each bone 

 to its circumference. This point may be near the center or one of the borders 

 of the bone. The ridges may be more or less interrupted or inosculating. 

 They are present on the lower jaw as well as on the upper. 



"Measurements. ,,., 



MM 



"Length of skull on base including symphysis 40 



Width of skull at quadrate articulations 36 



Length of mandibular angle from do 6 



Transverse diameter of orbit 5 



Length from posterior border of skull to orbit 18 



Width between nostrils 10" 



/i|_i^'^^ /f/^^\ NX A. Upper view of type skull showing sutures. 



/ ^^% \ /^/ \im\ ^^ pmx, premaxillary; mx, maxillary; /, 



/»~/ T^"^5?\ / / ^^VV v\ frontal; pt}, postfrontal; pto, postorbital; 



/^^V \ ^^^\ I I W \\\ •'' '"8"'' ^' P^^stal; int, intertemporale; 



I V/^^\\jW^\ / ^ \ \\\ -f?' squamosal; piq, prosquamosal; so, 



I ff'()~-/'\^^c<hj\ V, \M supraoccipital plate. The opening in the 



/ iUvA S 1 i2^\ \ r M middle line of the nose is a break. 



/M-in M \p \sa\ \ \mi\ ^' Diagram of lower surface of anterior end 



I ^^>^--- L ! _X^t 1 k ] °^ nose, showing enlarged vomerine and 



Lv«^ ^^^-^W V \ palat'ne teet!i. 



^^""a^ — '^^SJ?/ C \!zl C- Diagram of lower jaw. d, dentary ; s, 



A ^-''^-'^(ijij^ splenial; ang, angula'; art, articular. 



Fig 6. — T conangulus. No. 4569 Am. Mus. X > 



Revised description: Smallest of the genus. Skull not so flat in the post- 

 orbital region. Intertemporal present. Doubtfully a Trimerorhachis. 



Trimerorhachis leptorhyiichus Case. 

 Second Ann. Rpt. Dept. Geol. and Nat. Hist. Territory of Oklahoma, 1902-3, p. 64. 



Type: An imperfect skull. No. 3 50 University of Kansas. From north- 

 west of Orlando, Oklahoma. 



Original description: "A somewhat crushed skull indicates the presence 

 of a new species. The skull is imperfect, having lost the anterior end of the 

 muzzle and a portion of the articular region of the left side. The whole 

 skull is much longer and more slender than any known species of this genus, 

 its proportions being more those of Cricotus than T. insignis. The teeth 

 are mostly hidden, but one or two show that they are small and fine. The 

 orbits are directed more upwards than laterally and they were of greater 

 anteroposterior extent than lateral. The quadrate region of the skull pro- 

 jects quite far behind the articular portion (cotylus) so that there is a very 

 prominent excavation of the posterior portion of the skull. The ends of the 

 mandibles do not project posterior to the quadrate. The mandibles approach 

 each other, to contact in the posterior third of their length. The outer side 

 of the mandible is marked by longitudinal lines of sculpture. The whole 

 skull contracts sharply anterior to the occipital region, about opposite the 

 orbits. 



